Fiber reinforced polymer (“FRP”) structural reinforcing systems for tubular steel members exist for the communication tower and oil & gas industries. In addition to these systems, protection systems using non-metallic components exist for the offshore riser industry. Some systems are described in U.S. Pat. Nos. 5,330,807; 4,068,483; 4,728,224; 6,189,286; 5,591,265. Systems include the following.
Communication tower legs—Round steel tower legs are currently reinforced using pre-cured carbon fiber FRP half shells. These shells are engineered so that the majority of the carbon fibers are aligned along the axial y-axis and in the same direction that loads are transferred into the steel-composite legs. These carbon reinforcements are installed to resist buckling in the tower legs between lateral supports. If an external FRP hoop wrap is applied to the exterior of the carbon shell, its purpose is to provide protection against environmental elements and not to resist internal pressure in the pipe as provided in the current invention. Installation is made by structurally adhering carbon half shells onto steel pipe legs with spacer material located between carbon shells and steel pipe to ensure the proper the bond line thickness.
Risers—Round steel riser pipes are protected using non-structural material used as protective cladding against future impact damage onto riser pipe and to slow existing corrosion. Installation is made by adhering non-structural half shells onto steel pipe legs with spacer material located between these shells and steel pipe to ensure the proper the bond line thickness. Non-structural refers to shells that are produced of materials that can resist impact loads but not capable of resisting axial y-axis loads. Another method of protecting riser pipes includes a coating such as a FPR on the outside of a structure. The coating method of protection does not add internal pressure resistance to the pipe, as provided in the current invention.
There is a need in the art for an improved structural reinforcement system.